The integrated circuit used in this detector is uncommon today. We found it in a documentation from the 70s. Detection is done by an optical camera with LEDs and a photo sensor.
The frequency of this unijunction oscillator is determined by the crystal whose maximum frequency is...
This low power amplifier, with 2 W in charge of 16 ohms, was found in a Japanese magazine from the...
This circuit that emits siren sound can be used in a fire alarm. We found it in an old American...